In 2010, we initiated the construction of an insertional mutant library by the Agrobacterium mediated transformation of Cryptococcus gattii and isolated 30,000 mutant clones by the summer of 2011. This library will serve as a tool for identification of the genes that are involved in the manifestation of the pathobiological differences between the two species. During 2011-2012, we compared the pattern of nitrogen assimilation between C. gattii and C. neoformans and found striking differences in the utilization of D-amino acids such as D-proline and D-alanine. Furthermore, we discovered that the primary target organ for the two species in mice is different: the primary target organ for C. neoformans is the brain while for C. gattii, it is the lung. Since the host response toward the two species is clearly different, we initiated a study to compare the host-paracite relationship between the two species in 2013.